Scientists isolate antibodies that protect against various flu viruses

A team of researchers led by the Scripps Research Institute in La Jolla, California and the Crucell Vaccine Institute in the Netherlands has identified three broadly neutralizing human antibodies that protect against influenza B virus strains.

The research, published in the online edition of Science on Thursday, may help scientists to progress toward a universal flu vaccine that could be used during severe outbreaks. The antibodies can provide clues for designing a vaccine that could protect against multiple flu viruses on a long-term basis.

"To develop a truly universal flu vaccine or therapy, one needs to be able to provide protection against influenza A and influenza B viruses, and with this report we now have broadly neutralizing antibodies against both," Ian A. Wilson, the senior investigator of the study, said.

The three antibodies - CR8033, CR8071 and CR9114 - protected mice against typically lethal doses of the two main strains of influenza B. CR9114 also protected the mice against influenza A viruses by binding to a site on the hemagglutinin protein's stem, preventing the viruses from sticking to cells vulnerable to the flu.

"It prevents the hemagglutinin protein from undergoing the shape-change needed for the virus to fuse to the outer membrane of a host cell," Cyrille Dreyfus, the lead author of the study, said. "This appears to be a real weak point of the virus, because this epitope is highly conserved among influenza A subtypes as well as influenza B."

The viral epitope the CR9114 antibody connected with will now be studied extensively as a possible target for future universal therapies and vaccines. The antibody is the only known antibody found that broadly neutralizes influenza A and B strains.